Obituary: Professor Nicholas Kurti

NICHOLAS KURTI was the final link between physics at Oxford University and the remarkable group of scientists who emerged from the shadow of the holocaust in the 1930s.

Kurti and others in Germany and Eastern Europe were forced to recognise that their scientific genius would necessarily find its expression in countries other than those under Nazi hegemony, and their emigration to England, Canada and the United States is part of the history of science in the 20th century.

Kurti lived in Oxford for upwards of 65 years, yet he remained a quint- essential Mid-European and thereby epitomised a cultural as well as a scientific link with the early years. He so easily put one in mind of that remarkable city Budapest, which at the turn of this century produced far more than its fair share of the world's great physicists. Nicholas Kurti was born there in 1908, and went to the same school, the Minta-Gymnasium, as people like Edward Teller, Johnny von Neumann, Eugene Wigner and others. Perhaps some of their magic rubbed off on all those around them, for though Kurti was not in their league as a theoretical physicist, his lengthy career at Oxford was to confirm his reputation as one of the leading experimental physicists of his era.

Typical of his early years in Budapest was his desire to pursue seriously his study of the pianoforte. That in itself was perhaps not unusual, but when he sought suitable instruction and advice, one of his relatives took him along to a friend who was a piano teacher, one Bela Bartk. Kurti also recalled a young man several years his junior, who did enter the Conservatorium with a view to making a career in music: his name was Georg Solti.

Kurti moved to Paris for his undergraduate studies and then to Berlin to begin graduate work under Professor Francis Simon. This was in 1929. Barely four years later, the two of them packed their bags and headed for Oxford, where some 20 years later, Simon was to succeed Lord Cherwell as Head of Physics.

Even in these early years, when Kurti began his work on magnetic cooling, his energy and his relentlessly logical pursuit of a principle or an idea were apparent. For example, their work required as large a magnetic field as possible, but funds were limited as were the electrical sources to power an electromagnet. Kurti realised that one limit was the electrical resistance of the magnet windings. "Never mind," he said, "we will cool this magnet in liquid hydrogen, in order to reduce the resistance".

To quote from his memoirs:

I built the solenoid and with great expectations late one evening I pressed the switch which sent a current of 40 amperes through the coil. The result was spectacular - a deafening explosion, the apparatus disappeared, all windows were blown in or out, a wall caved in, and thus ended my pioneering experiment on liquid hydrogen cooled coils!

Things could only improve after that, which they certainly did. His experiments on the low temperature heat capacity of gadolinium sulphate were remarkable for their time. For physicists in that era, the new kid on the block was quantum mechanics. For people like Kurti the challenge was to bring the theory and methodology of thermo- dynamics to bear on the problem of obtaining quantum mechanical information about a system, from a purely macroscopic measurement such as heat capacity. What, after all, could be simpler than putting some heat into a body, and measuring the resulting temperature rise?

It took a great deal of experimental skill and physical insight to turn this into a serious measurement of quantum effects. This Kurti did, with gadolinium sulphate, where he was able to determine energy splittings a million times smaller than those observed, say, in the optical spectrum of the hydrogen atom. For all his great achievements later on, it was always clear that this early result gave him as much satisfaction as anything.

His Oxford career was interrupted to some extent by two events; first, the building of the modern Clarendon Laboratory, immediately adjacent to the University Parks, and second, the outbreak of the Second World War. Physics research at Oxford became but one aspect of the total war effort, and Nicholas Kurti made important contributions toward the problem of separating the isotopes of uranium, an essential step toward the eventual construction of the atom bomb.

Once things returned to normal, though, there were exciting times ahead. Kurti had turned his attention to the goal of reaching down the temperature scale into the millionths-of-a-degree-above-Absolute-Zero regime. The experiments were difficult, and certainly took all day to prepare, even when everything worked properly. Maximum excitement usually occurred around 2 to 3 am, which meant that the Clarendon had some features in common with the then well-known Windmill Theatre.

By the time Kurti was elected a Fellow of the Royal Society (in 1956) his nuclear cooling experiments had attracted world-wide attention. Never more attention, however, than in 1960, when he agreed to perform a millionth- of-a-degree cooling experiment live on national television, on Tomorrow's World. Kurti, instinctively the showman, was equal to it all, and the event was a great success.

His career thereafter is a litany of Prize lectures, Prize medals, visiting professorships and the like, all over the world. He was often amused - indeed, bemused - by the constant string of invitations he received to chair this, or join a panel for that, when on each occasion he would reply "But I don't know anything about that!" Effective he clearly was, if only as an irritant (his phrase) on governing bodies oozing complacency, but he liked to describe himself in this context by using a phrase from Isaiah Berlin, as a genuine charlatan!

Kurti had an instinctive distrust of bureaucrats and bureaucracy, of obfuscation and buck-passing. This led to fame of a different kind, when in 1967 he came into direct confrontation with British Rail. Returning to Oxford by train late one night, he found that he and several other motorists were trapped in the station car park. The automatic coin-operated barrier was jammed in the down position. The Daily Express best described what happened next, in their headline the following day: "CRACK! Man of Science bursts barrier!"

In many ways this was the perfect silly season story, and it ran for months. Kurti was charged with causing wilful damage to British Rail property, and was fined pounds 11.10s.6d. On appeal, he was granted an absolute discharge and he certainly had the last laugh. As the Oxford Mail put it: "It is enough to say that British Rail's action (or rather lack of it) over Dr Kurti's letter will not come as a surprise to hardened rail users in this city."

As bon vivant and connoisseur of fine food and wine, Kurti had a life- long love not just of food but of the art of cooking. Once he had formally retired in the mid-Seventies he pursued this interest with vigour, and again quickly found himself on television, bringing his physics knowledge to bear in the kitchen. His friendship with Raymond Blanc, chef supreme at Le Manoir aux Quat' Saisons, resulted in collaboration over the television series Raymond's Blanc Mange in 1995.

On the international scene, he was for some years co-organiser of the International Workshop on Molecular and Physical Gastronomy, held annually at Erice, Sicily. All this activity betokened a really serious interest in the magical processes associated with food preparation. He wrote of his personal belief that "the discovery of a new dish could be just as rewarding intellectually and just as beneficial to mankind as the discovery of a new inter-atomic force, or of a new low temperature phenomenon, or a new elementary particle, or of a new star".

To know Nicholas Kurti on a daily basis - as many did, for he continued to come to the Clarendon for coffee until just a few weeks before his death - was a very special experience. An endless source of stories, he loved a good joke, was always interested in what his friends were doing, and although at times he could be irritating beyond measure, there was always his humour and magnanimity to restore the balance.

Remarkably fit for someone his age, he nevertheless succumbed to the strain of two replacement hip operations in quick succession, and in the end it was just too much to bear.